It is useful to know the velocity or speed of a golf club head since the velocity affects the distance a golf ball will travel when the golf club head strikes the golf ball. An important factor in developing skill in golf is the ability of the player to strike the ball with the club head at high speed, and to strike with a consistent speed. For example, the distance which a golf ball will travel after having been struck with a golf club is dependent in large part upon the club head velocity at the point of impact with the golf ball. Accordingly, it is advantageous for golfers to be able to generate maximum speed of the golf club face.
The path followed by the club face when swung by a player is essentially arcuate. The characteristic of an implement swung in an arcuate path which imparts kinetic energy to a struck object is the linear or tangential velocity component of the implement at the point of impact with the object. This tangential velocity component of the golf club will be referred to hereinafter as the “swing velocity”. To train golfers to generate maximum swing velocity, it would be helpful to have some objective indicia of the swing velocity so that the effect of changes or refinements in swing technique on the swing velocity can be measured and readily seen by the golfer.
Remote sensors such as radar guns can be used to determine the velocity of the golf club head, but they are expensive and require persons other than the golfer to determine the velocity of the golf club head as it is swung. A velocity measurement device is known that fastens to the end of the shaft, above the golf club head, as described in U.S. Pat. No. 4,967,596 and as shown in FIGS. 1-2. But the attachable measurement device alters the weight and balance of the golf club and that affects the swing and the resulting club head velocity. The clip-on attachment also alters the appearance of the golf club in a way that is not pleasing. There is thus a need for an improved way to determine the velocity of a golf club head and a way that is preferably either pleasing to appearance or at least not unattractive and that does not require clipping something onto the outside of the club.
The interior of tubular golf club shafts can be viewed by looking through either end of the shaft—as long as the grip and head do not block the view. Thus far, there is believed to have been no need to view the interior of a golf club shaft through the wall of the shaft itself or transverse to the longitudinal axis of the shaft. Golf club shafts were originally been made of solid wood shafts, but are currently made of tubular shafts, using materials such as steel, titanium, fiberglass and graphite composite matrices to form tapered, tubular shafts. None of these shafts are believed to be sufficiently transparent or translucent to allow viewing of something inside the golf club shaft through the tubular wall of the shaft. Wood and metal are too opaque to see through. Prior fiberglass shafts are believed to have been colored and opaque, and graphite matrix shafts are black and opaque because of the carbon in the matrix.
While windows could be cut into tubular shafts to view the inside of the shaft, that is believed to never have been done, in part because the window would alter the structural integrity of the shaft and thus alter the shaft stiffness, bending, and other physical properties. A window would also make the stiffness non-symmetric and that has the effect of altering the shaft performance depending on how the golfer's grips on the shaft alters the orientation of the window relative to the golf ball being struck by the golf club head on the end of the shaft. These problems teach against viewing something through the wall of a golf club shaft.